It is now accepted widely that the presence of reactive molecules called reactive oxygen species or free radicals is generally at least one of causes of many human health abnormalities including aging, cancers, atherosclerosis, myocardial infarction, attacks, viral infections, lung abnormalities, bowel diseases, and neurodegenerative diseases and leads to aging and deterioration in health. These molecules, which are usual by-products of physiological reactions, are produced by enormous numbers of enzyme reactions indispensable to oxygen metabolism, for example, cellular respiration, or to the functions of the immune system (killing of foreign substances) and metabolism.
Particularly, mitochondria, subcellular organelles, transfer electrons in the electron transport system, while an electron leak always occurs. 2% to 0.2% of oxygen molecules used in respiration is reduced into reactive oxygen species. Furthermore, such reactive oxygen species are universally generated even in general environments. For example, ambient sources of reactive oxygen species encompass smoke, ionizing radiation, atmospheric pollution, chemical agents (carcinogens, many petrochemicals, biocides, dyes, solvents, cell division inhibitors, etc.), toxic heavy metals, and oxidized or rancid fats. Examples of the most general reactive oxygen species include superoxide radicals, hydroxyl radicals, singlet oxygen, and hydrogen peroxide. The reactive oxygen species encompass, in the broad sense, nitrogen monoxide, peroxynitrite, and lipid radicals such as alkoxyl radicals or lipid peroxyl radicals. For example, superoxide, hydroxyl radicals, nitrogen monoxide, and lipid radicals such as lipid peroxyl radicals or alkoxyl radicals are free radical molecules.
Free radical molecules have oxidative toxicity that causes structural damage to all biomolecules such as nucleic acids, proteins, and lipids in living organisms. Such molecular damage induces cellular abnormalities such as alteration in genetic codes, abnormalities in enzyme reactions, and lipid membrane degeneration and causes cytotoxicity. Thus, the free radical molecules have strong oxidizing power. A disorder caused by this oxidizing power is generally called oxidative stress. The accumulation of such oxidative stress may cause neurological disorders, endocrine disruption, increased allergy, vascular endothelial destruction, joint destruction, and inflammation at an individual level.
The oxidative stress is caused by strong oxidizing ability possessed by excessive reactive oxygen species or free radicals in cells. Most of superoxide anion radicals (O2−.) are generated by an electron leakage in the process from the Krebs cycle to the electron transport system in mitochondria. Moreover, O2−. is also generated by oxidase such as NADPH oxidase or xanthine oxidase. O2−. is converted to hydrogen peroxide by superoxide dismutase. This hydrogen peroxide is further converted for detoxication to water by glutathione peroxidase or catalase. Excessive O2−. reduces iron or copper, which is a transition metal. These reduction products react with hydrogen peroxide through the Fenton reaction to generate hydroxyl radicals (.OH). .OH, which is the strongest reactive oxygen species, indiscriminately reacts with nucleic acids, lipids, and proteins. A mechanism for detoxicating this .OH is unknown. Thus, the removal of .OH is the most important antioxidation process.
Protection from the poisonous influence of free radical molecules is found in molecules called antioxidants from diverse regions. In vivo free radical molecules and their related by-products may be converted to less harmful products by neutralization brought by antioxidants. Such antioxidants can be enzymes (superoxide dismutase, catalase, glutathione peroxidase, etc.), essential nutrients (beta-carotene, vitamin C and E, selenium, etc.), enormous numbers of endogenous substances (glutathione etc.), or food compounds (bioflavonoid etc.). Thus, humans have some natural inhibitors against free radical molecules in their bodies.
However, individuals suffer a great deal of damage by free radical molecules, in spite of the presence of such in vivo free radical inhibitors. Thus, it is obvious that effects including nutritional supplementation for the prevention of oxidation induced by free radical molecules delay human aging process and have big advantages to health promotion and the prevention of disease.
Meanwhile, the oxidation-reduction potential of hydrogen molecules is −0.42 V, and the oxidation-reduction potential of oxygen molecules is +0.82 V. Thus, hydrogen molecules have the intrinsic ability to reduce oxygen molecules. However, the oxidation-reduction potentials are indicators for oxidizing or reducing ability and merely indicate the final stage of oxidation-reduction reactions in an equilibrium state. Whether or not oxidation-reduction reactions actually proceed in vivo is another story. In general, the rapid progress of reactions requires catalysts or the like or requires promoting reactions at a high temperature. In cells having complex structures, the progress of oxidation-reduction reactions often requires their respective specific enzymes. Thus, it is impossible to predict whether hydrogen actually exhibits reducing power in vivo.
For example, according to the oxidation-reduction potentials, hydrogen and oxygen should be converted to water through a reaction. However, hydrogen and oxygen molecules dissolved in water are not converted to water through a reaction. Likewise, whether hydrogen molecules can reduce reactive oxygen species or free radicals, as described above, can be confirmed only by actual experiments. Judging from the oxidation-reduction potentials, hydrogen molecules are supposed to reduce superoxide, nitrogen monoxide, and hydrogen peroxide in an equilibrium state. Meanwhile, superoxide, hydrogen peroxide, and nitrogen monoxide have been demonstrated to play roles indispensable to living bodies. These roles are killing effects on invading bacteria, immune functions, defensive mechanisms against cancers, vascularization, vasodilation, spermatogenesis, neurotransmission, and so on. Thus, if hydrogen molecules rapidly eliminate these free radicals or reactive oxygen species in vivo through reduction, the hydrogen molecules should sometimes be harmful.
Water with a low oxidation-reduction potential has heretofore been prepared by electrolysis (see Patent Documents 1 to 3 below) or by dissolving hydrogen under pressure (see Patent Document 4 below). Of them, an aqueous drink with a low oxidation-reduction potential prepared by an electrolysis method merely exhibits alkaline properties attributed to OH− ions and does not contain hydrogen gas at a saturated concentration or higher. Such an alkaline aqueous drink has reducing power attributed to the OH− ions and therefore apparently exhibits reducing properties. However, this aqueous drink results in a high oxidation-reduction potential, when rendered neutral. This means that it exhibits apparent reducing properties. Moreover, the drinking of alkaline solutions in large amounts presents a health problem. Particularly, such alkaline solutions put a severe strain on the kidney and are therefore harmful to persons with renal damage. On the other hand, the alkaline solutions, if in appropriate amounts, are observed to have a few effects on persons with gastric hyperacidity. However, these effects are merely effects brought by the neutralization of gastric acid by the alkaline solutions and are not the effects of hydrogen gas or reducing power.
Moreover, another known method comprises mixing metal magnesium into an aqueous drink to thereby obtain reductive water. In this case, magnesium and OH− ions are generated simultaneously with hydrogen gas. Therefore, this reductive water is alkaline. Magnesium ions, if in appropriate amounts, can be expected to have health maintenance effects on human bodies, because they have been applied to laxatives and the like. However, the ingestion of such alkaline aqueous drinks in large amounts, as already described, works to inhibit the body function of being constantly neutral and is therefore dangerous. Rather, a drink prepared by simply dissolving hydrogen gas does not exhibit alkaline properties and therefore probably has higher safety.    Patent Document 1: JP Patent Publication (Kokai) No. 2001-145880A (2001)    Patent Document 2: JP Patent Publication (Kokai) No. 2001-137852A (2001)    Patent Document 3: JP Patent Publication (Kokai) No. 2002-254078A (2002)    Patent Document 4: JP Patent Publication (Kokai) No. 2004-230370A (2004)